Research On An Off-Axis Convex Aspheric Compensator

The application of off-axis aspheric surface in optical system has many advantages: reducing the size of instrument,reducing the weight of system,simplifying the structure of system,reducing the central occlusion,increasing the field of view,improving the imaging quality and so on.With the improvement of optical system performance requirements,the relative aperture and off-axis amount of off-axis aspheric surface are increasing,and the surface shape accuracy requirements are also increasing.Accordingly,the surface shape detection accuracy requirements are also higher and higher.This puts forward higher requirements for high-precision surface shape detection,and the detection of off-axis convex aspheric surface is still a breakthrough.Firstly,the testing methods and development of convex aspheric surface are introduced.Then,based on the third-order aberration theory,the spherical aberration and monochromatic aberration of aspheric surface are calculated.The calculation method is introduced and applied to the aberration calculation of off-axis convex aspheric surface;For the surface inspection of large diameter off-axis convex aspheric mirror,the commonly used half transparent and half trans Hindle inspection method is improved.A special structure compensator group is designed,and the error analysis of the processing and adjustment of the compensator is carried out.At the same time,the simulation optimization and tolerance analysis of the whole compensation detection system are carried out;In addition,a scheme to remove the material error is designed,and the corresponding simulation results are given;In addition,the actual optical inspection system is built,the experiments of system error removal and surface shape inspection are completed,and the corresponding results are given.At the same time,it lays the foundation for extending this design to the detection of larger diameter convex aspheric surface.Finally,in order to verify the reliability of the theoretical design,the surface shape results are compared with the results of our master mirror test,and the residual error is within the error range to verify the correctness of our theoretical design.The final measurement data can guide the optical processing,so that the measured mirror can achieve the required surface accuracy,which also proves the correctness and feasibility of the proposed method.In this paper,based on the existing aspheric testing technology,the testing method of off-axis convex aspheric surface is studied1.The transmission Hindle compensation mirror group is improved,and the meniscus lens is used to replace the spherical lens in the traditional compensation mirror.The optical path is optimized and analyzed by software.The theoretical accuracy of this scheme is 0.0085 λ。2.The single meniscus lens is changed to compensate,the transmission compensation mirror group compensation method is proposed,and the design of off-axis convex aspheric surface detection scheme is completed.After optimizing the optical path,ZEMAX software is used to calculate the error of the optical path structure.On this basis,the experimental measurement optical path is built to verify the detection scheme.The system error is analyzed by experiments,and the results verify the effectiveness of the compensator design.